The invention relates to an apparatus and method for controlling the pressure in a fluid compressing system, and more particularly to an apparatus and method for controlling the pressure in a dual pressure regulation fluid compressing system.
Conventional air compressors are designed to operate at a rated pressure such as, for example, 200 psig. Certain conventional compressors have pressure regulators that maintain air pressure in a fluid outlet or storage tank at the rated pressure. These compressors generally include sufficient power and cooling systems to allow the use of the compressor at the rated pressure under all loads and ambient temperature conditions without overheating the compressor.
However, certain compressed air powered machines benefit from air pressures higher than the rated pressure of the available air compressor. For example, certain drilling equipment is significantly more productive when supplied with compressed air in the range of 215-225 psig than when supplied with compressed air at the regulated 200 psig. In order to obtain a compressed air supply in the 215-225 psig range from a compressor rated at 200 psig, the user of the drilling equipment adjusts the regulator to regulate the compressor to 220 psig. The users"" actions to adjust the regulator have led to compressor damage. Regulators and safety valves were damaged due to the excessive and repeated opening.
To accommodate the demand for a higher air pressure and to prevent damage to the compressor, a dual regulation system was developed. The dual regulation system employs two regulator valves (set at 200 and 220 psig for example) and a three-way valve to allow a user to select the pressure regulation setting.
While the dual regulation system eliminated the need for the user to tamper with the regulator, an additional problem developed. The compressor does not have sufficient cooling margin to provide the higher pressure at a high ambient temperature and/or a high load. Thus, sustained operation of the compressor at the higher setting (e.g. 220 psig) at a high ambient temperature or high load could cause compressor damage. Accordingly, there remains a need for a pressure regulation system that reduces the operating pressure automatically in response to high ambient temperature.
A system for controlling a compressor is provided. The compressor has a fluid outlet. A temperature sensor is positioned to sense a temperature of a compressed fluid in the fluid outlet. A first pressure regulator is provided for maintaining the pressure of the compressed fluid at a first predetermined pressure. A second pressure regulator is provided for maintaining the pressure of the compressed fluid at a second predetermined pressure, which is greater than the first predetermined pressure. A control system is provided for selecting either the first or second pressure regulator to maintain pressure of the compressed fluid. The control system is configured to select the first pressure regulator when the temperature sensor senses that the temperature of the compressed fluid exceeds a predetermined temperature. The control system may include a valve which is operated to select one of the pressure regulators. Each pressure regulator may be operatively connected to the fluid outlet of the compressor and has an open and closed condition, wherein the open condition reduces the pressure of the compressed fluid. The control system may further include an isolation valve that is operatively connected to the temperature sensor and opens to enable the first pressure regulator to control pressure of the compressed fluid. The control system also may include a three-way valve having a first and second position, wherein in the first position the first pressure regulator controls the pressure of the compressed fluid and in the second position the second pressure regulator controls the pressure of the compressed fluid.
In an alternative embodiment of the present invention, an apparatus for controlling a compressing system having dual pressure regulation is provided. The apparatus includes a control device having a fluid inlet and being operatively connected to the compressor for controlling a compressed fluid output of the compressor. A first fluid passage connects the compressor outlet to the fluid inlet of the control device. A low pressure regulator is positioned within the first fluid passage and has an open and closed condition. The low pressure regulator opens to permit compressed fluid to pass through the low pressure regulator when compressed fluid pressure in the compressor outlet exceeds a predetermined low pressure. A second fluid passage connects the compressor outlet to the inlet of the control device. A high pressure regulator is positioned within the second fluid passage and has an open and closed condition. The high pressure regulator opens to permit compressed fluid to pass through the high pressure regulator when compressed fluid pressure in the compressor outlet exceeds a predetermined high pressure. A shut-off valve is in series with the low pressure regulator and is controlled by the temperature sensor so that the shut-off valve opens when the temperature exceeds a predetermined maximum temperature, and closes when the temperature drops below a predetermined minimum temperature.
A third fluid passage may be provided to connect the outlet of the pressure regulator to the inlet of the control device. A three-way valve may be positioned between the second and third passages and the inlet of the control device. The three-way valve has a first position operatively connecting the third fluid passage to the control device, and a second position operatively connecting the second and third fluid passage s to the control device.
The control device may be an air cylinder for controlling a throttle of the compressor. The control device may also include an air cylinder for controlling a position of an air inlet valve to reduce an amount of fluid that enters the inlet of the compressor. The control device may also be a combination of the throttle controlling air cylinder and the inlet valve controlling air cylinder.
In yet another alternative, the present invention provides a fluid compressing system. The system includes a compressor and a controller that controls the compressor to reduce the pressure of the compressed fluid when the temperature of the compressed fluid reaches a predetermined temperature. The controller may be operatively connected to a throttle and/or inlet valve of the compressor. A pressure sensor may be positioned to sense the pressure of the compressed fluid in the outlet of the compressor. The controller controls the compressor to reduce the pressure of the compressed fluid when the temperature of the compressed fluid reaches a predetermined temperature and the pressure of the compressed fluid reaches a first predetermined pressure. The controller also controls the compressor to reduce the pressure of the compressed fluid when the pressure of the compressed fluid in the outlet reaches a second predetermined pressure.
The controller may be configured to have two states: a first state in which the controller controls the compressor so as to maintain a first pressure in the fluid outlet of the compressor, and a second state in which the controller controls the compressor so as to maintain a second pressure in the fluid outlet of the compressor. The controller operates in the first state when a temperature of the compressed fluid in the outlet exceeds a first predetermined temperature, and operates in the second state when the temperature falls below a second predetermined temperature.
A method for controlling a dual regulation fluid compressor system is also provided. The method includes the steps of: operating the compressor system at a high pressure setting so that an amount of compressed fluid produced by the compressor is reduced when pressure of the compressed fluid exceeds a predetermined high pressure; sensing a temperature of the compressed fluid; shifting the compressor system from the high pressure setting to a low pressure setting when the sensed temperature exceeds a first predetermined temperature; and operating the compressor system at the low pressure setting such that an amount of compressed fluid produced by the compressor is reduced when pressure of the compressed fluid exceeds predetermined low pressure. The method may include shifting the compressor system from the low pressure setting to the high pressure setting when the sensed temperature falls below a second predetermined temperature.
In an alternative embodiment, a method for controlling a dual regulation fluid compressor system is provided. The method includes the steps of: sensing a temperature of compressed fluid in an outlet of a compressor, reducing an output of the compressor when the temperature exceeds a first predetermined temperature and a pressure in the outlet exceeds a predetermined pressure. The method may further include the step of increasing the output when the temperature falls below a second predetermined temperature.
If is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.